Reducing Tyre Pressure

According to the DTI, more than 48million tyres are disposed of in the UK every year, which raises the question of what to do with them. Steve Waite, project manager for tyres at the Waste & Resources Action Programme (WRAP) explains how the market for used tyres is increasing and ways in which recycling companies can transform this waste into a new business opportunity.

Setting minimum requirements for recycled content by value for projects is a growing trend among some of the construction industry’s most influential clients in the UK.

The Scottish Executive, Building Schools for the Future Programme and the National Offenders Management Service demand 10% while the Olympic Delivery Authority has set a target of using 25% recycled aggregates by weight.

These are all examples of clients leading the way towards more sustainable construction, by setting minimum recycled content requirements. Over the next year contractors can expect this to become typical practice.

And for contractors worried about the financial impact of meeting or exceeding these requirements, substituting virgin with recycled materials can be cost neutral and even cost saving.

Another knock-on effect is improved sustainability credentials of the project by diverting waste from landfill sites. This helps build long-term relationships with clients by helping them to meet their sustainability targets.

The role tyres can play

In 2003 the EU Landfill Directive banned whole tyres from landfill, in July last year shredded tyres followed. The ban now applies to most tyres less than 1.4m in diameter.

The combination of this ban and growing client requirements for higher levels of recycled content has created a lucrative market for tyre-derived materials in construction products and applications.

Ensuring a greater understanding of these opportunities and how to take action is crucial. Tyres are 100% recyclable – including the fibre and steel – and tyres derived materials can be used in different applications across various sectors, including construction, landscaping, civil and landfill engineering, and home and garden.

At WRAP we offer funding for research and development projects to help the industry address barriers restricting the greater use of reprocessed tyres, including quality assurance. And so far 26 projects have been completed since the tyres programme was set up in 2005.

One such project in Nottingham recently completed by engineering consultancy Scott Wilson showcased the use of post-consumer tyres in delivering sustainable construction options for public rights of way.

Asphalt surfaces are durable and smooth but the material can be too hard for comfortable running or horse riding leading to jarring. Softer surfacings, such as grass or sand provide the required give. However, maintenance costs are much higher.

Tyres provide the perfect solution, whether as a sub-base layer or incorporated into the surface. They give the path the required flexibility. The success of the Nottingham project has already brought in interest from another rights-of-way officer from another council.

But surfacing solutions are not the only application. Research findings also indicate that over 100,000tonnes of steel and 17,000tonnes of fibre could be recovered from used tyres generated in the UK each year. In practice, only a third of these quantities is currently recovered (see in-brief page 3).

The use of tyre bales in civil engineering applications such as lightweight embankment fill, road foundations over soft ground and drainage layers, is another opportunity.

Although there is no current standard definition of a tyre bale, WRAP has developed PAS108 specification which defines it as “…a result of compressing and securing whole tyres into a bale within dimensional and density limits.”
It provides a means of reusing them while at the same time reducing the demand for primary aggregate. Also, bales offer permeability comparable to gravel – high porosity, low bulk density, and good frictional response and stiffness.

Lifespan of the product depends on application. In the case of embankment where they are covered by soils and are not exposed to ultra violet light or to extreme temperatures, they can last up to 200years.

Bales were used on a project near Sussex Downs which saw a 180m long section of rutted, unsurfaced road replaced. Normally the rutted area would have been excavated and the soil replaced with free-draining granular aggregate. But not this time.

As an alternative, the excavated soil was replaced by tyre bales and a 150mm layer of crushed natural stone was used to form the road surface. This resulted in cost savings as well as avoiding the use of natural aggregate.

But as well as an increase in user confidence for recycled used tyre products there also needs to be an improvement in capacity for recycling. And WRAP is helping recycling companies meet the growing market by investing in reprocessing infrastructure.

We provide capital funding to companies seeking to set up or expand tyre recycling facilities, which is particularly important for projects being developed by SMEs. And the focus is very much placed on those looking to deliver added-value processing.

For example, with 78,000tonnes of steel and fibre going to waste each year, an investment in infrastructure to increase capabilities to recover steel and fibre from scrap tyres is the type of project WRAP is keen to support. So contact me with your ideas.

Also, our eQuip Residual Value Guarantee (RVG) scheme helps recycling companies to secure the financial help by guaranteeing the future value of the equipment to be leased, reducing the risk for the finance provider and ensuring competitive leasing rates.

In short, the EU Landfill Directive banning tyres from landfill, coupled with emerging research into the development of end-use applications, has presented both recycling companies and contractors with significant business opportunities.

Now is the time to invest in the market for recycled and reused tyres by improving or expanding your recycling facilities and WRAP has a wealth of resources to help you, from case studies through to financial support and statistics.

WRAP construction: 0808 100 2040
eQuip scheme: 01494 689500

A brief Q&A on tyre recycling

What is in a tyre?
A range of things. It is a complex mix of synthetic and natural rubber, carbon black, steel, textiles, and chemical and mineral additives.

So, are scrap tyres a hazardous waste?
Although the Hazardous Waste Regulations do not apply to scrap tyres they may be contaminated with hazardous materials such as oil. If so they are treated as hazardous.

What tonnage of scrap tyres are recovered in the UK?
Because of the Landfill Directive all tyres need to be recovered. According to the DTI scrap tyre arisings in 2005 were 487,000tonnes. Around 7% are exported (34,000tonnes).

But I’ve seen the Simpsons. What about tyre stockpiles?
A stockpile is an area where a build up of tyres has occurred mostly through illegal dumping in remote unlicensed areas to avoid paying the gate fees at licensed sites such as transfer stations. A study by WRAP and ERM in 2005 identified 30 major stockpiles in the UK, the biggest holding over 1million tyres, such as Knighton in Heyhope and Old Hamphole Quarry.

OK, so what technologies are available for reprocessing scrap tyres?
Quite a few. They tend to break down into re-use, mechanical, thermal, and novel. Re-use involves re-treading tyres to go back on to vehicles, while mechanical includes shredding, granulation and baling. Thermal reprocessing includes pyrolysis and devulcanisation as well as incineration and cement kiln combustion. Novel technologies include using bacteria to break down tyres, cryogenics and microwaving.

Each will produce a different end material. For example, mechanical processes will produce various sizes of shred, chip or granulate. Cryogenic processing will produce similar materials, but the rubber crumb will be more regular in shape and smoother than crumb from ambient tyre processing. Incineration and co-combustion, on the other hand, will consume the rubber and textile, with the steel being discharged as part of the bottom ash.

So what is the difference between shredded, crumbed, granulated, chipped or powdered scrap tyres?
WRAP has recently developed Publicly Available Specification PAS107 giving definitions for the various types of recycled tyre material by size. Cuts are more than 300mm, shredded tyre is 50-300mm, chips are 10-50mm, granulate one-10mm, and powder less than 1mm.